Development of test kit for protein allergens in natural rubber latex and rubber products

Abstract

Protein allergens in natural rubber latex (NRL) and NRL products may cause life threatening allergenic hypersensitivity type I in hypersensitive users. Hence the objectives of this research are to develop a new grade of concentrated latex with low allergenic proteins and to develop the test kit for protein allergen determination in natural rubber latex and rubber products. Alcalase enzyme was used in the production of deproteinized concentrated latex (DPCL). The physical properties of DPCL obtained from this research meets with ISO 2004 specifications, with especially low volatile fatty acid (VFA) of 0.079 % or 50 % of control latex, and mechanical stability time, MST (1486 s) higher than control concentrated latex (799 s). The consistent low protein quality of DPCL were evident by 0.07 +- 0.07 % total nitrogen content and 17 +- 12 mg/g extractable protein (WEP) content, which were 70 % and 95 % reduction from control respectively. There was no WEP inthe molecular weight (Mw) range of 14- 97 kDa or no major allergens. The test kit for latex protein allergens was developed by using latex serum proteins as standard protein comparing with BSA and ovalbumin in the total protein determination by modified Lowry and Bradford methods. Latex serum proteins showed similar protein quantities evaluated from the standard calibration graphs of BSA and ovalbumin. The Mw of latex serum proteins studied by Sephadex G- 75 column and SDS- PAGE showed the first dominant protein peak (P1) at 30 kDa, followed by the second peak at 20.1 14.4 kDa and P3 at 4.7 kDa respectively. The latex serum proteins were used as standard latex protein allergens in skin prick test compared to commercial latex allergens in 112 volunteers which were separated into 2 groups: 1) atopic health care workers who had been sensitized by latex gloves and 2) general atopic patients at the Dermatological Department. The results of SPT showed 19.7 % positive to commercial latex allergens and 46.5 % positive to latex serum proteins in health care workers. In general atopic patients, positive SPT 9.8 % and 15.5 % were observed with commercial and latex serum protein allergens developed in this research. In addition, deproteinization of latex and solid rubber can reduce the prevalence of latex allergy to 1- 3 %, while control latex showed 8- 10 % positive in sensitized health care workers. In conclusion the developed protein allergen test kit can be used to study the prevalence of latex allergy in high risk groups and to evaluate the quality of low- protein rubber products to some extent.